No error message no display output

I?m using this version of R

R version 2.13.2 (2011-09-30)
Copyright (C) 2011 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: i386-pc-mingw32/i386 (32-bit)


2012/5/5 Trying To learn again<tryingtolearnagain at gmail.com>

Hi all,

I?m re-starting (as my name indicates) my little knowlegde of CRAN R.

I made this function time before but I don?t know where is the error
because nothing appears as an error but the histogram plot doesn?t appear.
Should I install some special library to run sapply?


pru<-function(){

randz<-matrix(rnorm(200000),100,2000)

H<-matrix(0,100,2000)


for (j in 2:2000){
for (i in 2:100){
H[1,]<-randz[1,]
H[i,j]<-H[i-1,j]+randz[i,j]


}}

hy<-nrow(H)-1

estima<-H[2:nrow(H),]

estima2<-H[1:hy,]


a<-estima
b<-estima2


mycoef<- function(x, y) coefficients( lm(y ~ x-1) )

rest<- sapply(2:2000, function(i){
                y<- a[,i]
                x<- b[,i]
               mycoef(x,y)
                }
             )



print(summary(rest))

hist(rest,col="blue",breaks=seq(0.6,1.05,0.01),prob=TRUE)
lines(density(rest,bw=0.03))
rug(rest)



}

Many Thanks???

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